Electric bake oven



March E@ 1926.

J. U. MANISCHEVWTZ ELECTRIC BAKE OVEN 4, 1921 6 Sheets-Sheet l Filed Feb.

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J. U. MANIESCHEWWZ ELECTRIC BAKE OVEN AL, 1921 6 Sheets-Sheet Filed Feb.

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J. U. MANISCHEVWTZ ELECTRIC BAKE OVEN Filed Feb. 4, 1921 6 Sheets-Sheet :3

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J. U. V'ANSCHEVVl-FZ ELECTRI C BAKE OVEN Filed Feb. 4, 1921 6 Sheets-Sheet 4 March 30 1926.

J, U. MANlSCHEWlTZ ELECTRI C BAKE OVEN Filed Feb. 4, 1921 6 Sheets-Sheet 5 J. U. MANISCHEWITZ March 30 1926.

4 ELECTRIC BAKE OVEN Filed Feb. 4, 1921 6 Sheets-Sheet 6 Patented Mar. 30, 19.26.

" UNITED STATES JACOB U. MANISCHEWITZ, OF CINCINNATI, OHIO.

ELECTRIC BAKE ovEN.

Application led February 4, 1921. Serial No. 4423409.

To all whom t may con-cern.'

Be it known that I, JACOB U. MANIsoHE- wI'rz, a citizen of the United States of America, and residentof Cincinnati, in the county of Hamilton and State of Ohio, have invented new and useful Improvements in Electric Bake Ovens, of which the following is a specification. v

My invention relates to an electrical method and apparatus for heating ovens in which are employed a plurality of electric heating elements; and the main object of my invention is to provide a method of heating electric heating elements whereby any desired temperature may be effected without loss of electric current, that is, all the electric current consumed is for heating purposes only.-

Another object is to provide a simple system of wiring for the electric heating elements, eliminating the complicated and diicultly-accessible system nowused.

I attain these objects by utilizing voltages of different electromotive force as hereinafter fully described, and particularly pointed out in the claims.

Since electric heating elements are rated' by wattage for their heating capacity, it is manifest from the following fundamental elementary electrical formulas:V Amperes multiplied byl volts equal watts, and watts divided by volts equal amperes, that, by keeping the amperage the same and varying the voltage, the resulting wattage is changed proportionately, and consequently temperature is similarly effected' without any loss .of electric current or energy.

My invention, then, consists lin an electrical method and apparatus for supplying or directing electric currents of different voltages to electric? heating elements f located within an ovenchamber to effect different temperatures, and means, preferably exterior of the oven, adapted to direct said electric currents of different' voltages to the electric heating elements.

The accompanying drawings form a part of this specication, and represent what applicant considers the best means for carrying outthis invention. I do not limit myself however, tothe precise arrangement and details as herein disclosed, as other modes of applying the principle of my invention may be employed instead of the' one explained,

change being made as regards'the arrangement and mechasm hereln `dlsclosecl, pro.-

yided the means stated by any of the following claims or the equivalent of such stated means be employed.

In the said annexed drawings Figure 1 .is a side elevation of a stationary oven embodying my invention, showing electric heating elements at the` bottom only; Fig. 2, a side elevation showing electric heating elements at both top and bottom of the oven chamber; Fig. 3, a side elevation (broken out between ends) of a traveling oven embodying my invention, vshowing electric heating elements below 'a movable member; Fig. 4, a side elevation (broken out between ends) showing electric heating elements both above and below a movable member; Fig. 5, a cross section of the oven taken at line A-B, of Fig. l; Fig. 6, is a cross section of the: stationary oven, but with electric heating elements at the top of the oven chamber; Fig. 7, is a cross section taken at line C-D, of Fig. 2; Fig. 8, is a cross section taken at line E-F, of Fi 3; Fig. 9, is a cross section taken at line .-H, of Fig. 4; Fig. 10, a conventional diagram showing the main supply wires, the feed wires leading to the electric heating elements, and a switch means interposed between said main supply wires and said feed wires for directing electric currents of different voltages to said feedwires Fig. 11. is an enlarged view of the knife switch forming a part of the switch illustrated in Fig. 10;"

Fig. 12, is a cross section of th'e knife switch taken at line Il, of Fig. 11, further illustrating the positive and negative terminal construction; Fig. 13, a conventional diagram of the electric heating element employed in my improvedoven; Fig. 14, a conventional diagram showing a method of wiring electric heating elements now in use.

chamber of an oven' in which my method of electric temperature control and heating is incorporated, 2 and 3 are the sidewalls of the oven chamber, 4 the bottom wall and 5 the top wall. The front and rear oven chamber walls are denoted by the numerals 6 and 7 respectively Numerals 8 and 9 denote suitable foundation side walls or footings and l0 and l1 denote suitable foundation end walls or footings. The construction of the walls 2, 3, 4, 5, 6 and 7 ofthe oven chamber is such as is necessary to prevent radiation of heat; and said walls generally are lined with metal 91 lire-brick, and `prefer- :Referringf-to the drawings, 1 denotes the l ably with a'refractory material, denoted by A12, 13, 14, and 16, but being of a suitable construction it is not specified in detail.

Electric heating elements 17, shown conventionally, and mounted in suitable frames 18, are mounted in the oven chamber 1, at the bottom, as shown in Figs. 1 and 3, or at the top, as shown in cross section at Flg. 6, or at both bottom and `top, as shown at Figs. 2 and4, but I do not limit myself to these locations of the electric heating elements. By my improved method, the degree of heat inrall or any of the several elect-ric heating elements 17 may be regulated. to suit specific Ineeds, since a uniform electric current may be directed or 4supplied-to the electric heat- Jmeans 26, specified ater.

ing elements simultaneously, but of different voltages.

With some systems now in use that are known to applicant several electric heating elements lare wired together `in series and series parallel and arranged to be thrown in in varying quantities to effect the degree of temperature required. With this method, complicated wiring is necessary, and very inaccessible; further, temperaturecontrol is effected only by reducing or increasing the number of electric heating elements thrown in, and for low temperatures many of the electric heating elements will be cut out altogether, resulting in uneven distribution of heat, besides being detrimental to the electric heating elements that are in use. Fig. 14 shows a form of wiring for electric heating elements, and is described more fully later on. Fig. 13 shows a conventional diagram'of an electric heating element, the temperature of which is effected by directing electric current of different voltageto said electric heating element b means vof the switch In other methods, the electric heating elements. are slidably mounted so that their proximity to the goods being baked may be regulated vto effect the desired temperature, resulting in a great loss of electric current and hence very inefiicient.

Main supply electric wire conduits 19 andl 20 are shown conveying the several main supply wires 21, 22, 23, 24, and 25 of different voltages, leading from a main source of supply. Switch means 26, of any suitthe switch means 26, and pivoted on stud 54, or any other suitable methods may be employed.

Assuming that a selected assortment of voltages such as 220, 165, 110, 82%, and 55, carried by the wires 21, 22, 23, 24 and 25 respectively, are the most desirable to effect a selection of temperatures, and that the greatest heat is necessary to fire the oven at the beginning of operations, the knife switch 42 is thrown in the terminals 27 and 28. As it becomes necessary to reduce the temperature, the knife switch 42 is pulled out of the terminals 27 and 28 and thrown in to either the terminals 29 and 30, 31 and 32, 33 and 34, or 35 and 36, as is necessary to effect the temperature desired. Line 48 carries the common wires to complete the circuit for the several main supply wires 21, 22, 23, 24 and 25, and said feed wires 48 partake -of the same voltage as the main supply wires that said feed wires 48 are connected with by means of the knife switch 42. In the several drawings, the switch means 26, shown enclosed and mounted directly across the main supply wires 21, 22, 23, 24 and 25, embodies the entire switch mechanism, shown conventionally in Fig. 10, and connects to said main supply wires by the wires 37, 38, 39, 4() and 41. as shown in said Fig. 10.

The main supply wires 21, 22, 23, 24 and 25 are composed of two wires each-a positive wire and a negative wire. Also, the feed wire 48 is composed of two wires-a positive wire and a negative wire. So also, the supply wire 93, specified later, is composed of two wiresa positive wire and a negative wire. The positive wires are denoted by and the negative wires by Referring to the conventional outline shown in Fig. 13, it will be seen that the electric heating element 17 has but twoterminals, the positive terminal 51 and the negative terminal 52, and but one set of feed wires 48 connecting these said terminals. F or a comparison, applicant shows'. in Fig.

V14, a conventional layout of electric heating elements in which my method of direct` ing different voltages into the electric heating elements is not incorporated. The electric heating elements 57 58, 59, 60, 61, 62, 63, and-64, are connected by wires 65, 66.

ino

and 67 to any approved form of switch 68, and hence not shown in detail. For a full load, by turning the knob 9:2 to full,

appropriate contacts in the switch 68 connect the wires 65, 66 and 67 with main supply wires 93, and hence current vis directed to all the electric heating elements 57, 58, 59. 60,

61, .62, 63 and 64. vFor a medium load,l

, current is directed to allthe electric heating elements 57, 58, 59, 60, 61, 62, 63and 64, but only one-fourth the elec-tric current is carried by each said electric heating element because the said electric heating elements are thrown in series. It is manifest, therefore, by this method of wiring a plurality of electric heating elements and controlling them by a single switch means 68, if one of the electric heating elements burns ont.

while operating at other than a full load,y there 1s an unbalanced or uneven distribution of heat; and, if two of the electric heating elements in a series parallel connection (as shown in Figflt) burn out, as electric heating elements 57 and 58, all the electric heating elements (57. '58, 59 and 60) connected in series parallel go out automaticallv. i

It is sometimes desirable to -place the articles on a movable member 69, instead of.

on a hearth-plate 70. The movable member 69 preferablyis an endless carrier, and

carries the articles through the baking chamber 1. through suitable openings 70 and 71 in the oven ends. In other types of ovens but one front opening 70 is required through which to place and remove the articles. The movable member or endless carrier 69 is rotatablymounted on suitable drums 7 2 and 73, and supported on members 7 4 suitablymounted in the oven chamber l. Drums72 and 73 are suitably mounted on shafts 87 and 76 respectively. Drum 7 3 may be driven by any suitable means, such as by means of a gear 75, suitably mounted on shaft 76, and a mating pinion 77, suitably mounted on shaft 78. On shaft 78 I have shown gear 79, which meshes with pinion 80, mounted on shaft 81 of a variable speed machine 82 of any suitable construction, and hence not specified in detail. p Motive power is applied to the variable speed machine 82 by any suitable means, such as by means of a drive pulley 83, mounted on shaft 84, and drive belt 85, connected with any suitable source of main or prime motive power not .shown in the drawings. Suitable bearings 86 and 88 are provided for shafts 87, and 76 and 7 8. A discharge plate 89, at least the full width of the movable member 69, and secured in position by any suitable means, permits finished articles to slide off the movable member 69 to any desired location.

For an oven of the traveling type it is desirable to vary the oven temperature. at various positions of the oven length` chiefly to overcome the fact that heat is carried along `by the movable member. To the accomplishment of this and related ends I` prefer to place the switch means 26 at several poitions of the oven length, as shown in Figs. 3 and 4, the number of said switch means 26 depending on the length of the oven' and the kind of articles to be treated. The endless carrier 69V usually is returned through openings 9() and 91 in the foundation end walls 10 and 11 respectively.

ln the stationary types of ovens it also is advantageous to be able to control the several electric heating elements independently; or, a few of the electric heating elements may be connected (wired in parallel) to compose a unit, said unit having its inA- dependent switch `means 26 adapted to direct different voltages to the electric heating elements to eiiect diii'erent temperatures.

l have not shown any outlets for the escape of vapors, gases or fumes, as these may be located in position appropriate to the articles being treated.

Having thus described my invention, what 1 claim as new, and desire to secure by Letters Patent, is:

1. llny an oven having an electrically 'heated chamber, electric heating elements in the chamber, a positive terminal and a negative terminal on each heating element, a multiple throw two pole switch for each heating element, an electrical connector connecting the terminals of the heating elements with the poles of the switch, a plurality of electrical main supply lines of dif ferent volt-ages, disposed without the oven, pairs of contacts about the switch for re ceiving the polesthereof, each pair of con tacts being electrically connected with one of the main lines for selectively connecting an electrical current of a given vvoltage to a heating element.

2. ln an oven the combination with a heating chamber, electrical heating elements within the chamber, a two p ole multiple throw switch for each heating element, a pair of lead wires connecting each heating element to the poles of one of the switches, a plurality of electrical main supply lines of different voltages, pairs of contacts for receiving the poles of a switch, each pair of contacts having electrical'conneetion with the positive and negative wires of one of the electrical main Supply lines.

3. In an oven having an electrically heated chamber, an electric heating element in the chamber, a positive and a negative terminal on the heating element, a plurality of electrical supply circuits carrying electricity of different voltages each circuitvcomprising a negative and positive line disposed exteriorly of the oven, and a multivoltage switch for selectively connectingl the positive and negative terminal of the. heating element with a positive and negative line of a supply circuit.

4. In a device of the class described the combination with an ove-n, of an electric heating element `disposed in the oven, a plurality of electrical main supply circuits carrying electricity of different voltages disposed exteriorly of the oven, and a sWitching means for selectively connecting the heating element with the various main supply circuits for effecting diferent temperatures of the heating element within the oven.

5. In a device of the lclass described the combina-tion with a heating element, of 4a plurality of electrical supply circuits of different voltages, and a switch for'selectively connecting the heating element to any of the different circuits.

In testimony whereof, I have hereunto subscribed my name this lst'day of J anuary7 1921.

JACOB U. MANISCI-IEWITZ. 

